The present invention relates to a device for removing a film-like image forming substance from a recording medium for thereby regenerating the medium.
Recent office automation has brought about the consumption of a great amount of printer sheets and copier sheets and, therefore, a great amount of waste sheets in offices. Most of the waste sheets are simply disposed of. The disposal of the waste sheets not only needs an extra cost, but also deteriorates the local environment due to the processing of the sheets. Moreover, it deteriorates the environment in the global scale due to excessive lumbering.
It has been customary to recycle the sheets by removing ink therefrom, immersing them in a liquid, and then making new sheets. Today, an advanced kind of sheets are under development which can be recycled for copying and printing purposes if text images formed thereon are removed by cleaning. For example, Japanese Patent Laid-Open Publication 4-670043 discloses a sheet having a substrate whose surfaces, particularly one surface, is treated to have a parting ability. The substrate with the parting ability is provided with a mark to be distinguished from ordinary sheets. However, this kind of sheet is special and not feasible for a copier because an image cannot be stably fixed thereon. Japanese Patent Laid-Open publication Nos. 1-101576 and 1-101577 each teaches a method of removing an image from a sheet by treating the sheet with ultrasonic waves in an organic solvent, which dissolves a film-like image forming substance (toner) on the substrate of the sheet. The organic solvent, however, brings about environmental pollution as well as hazards due to its inflammability and toxicity. Hence, this kind of scheme is not feasible for offices and homes. Japanese Patent Laid-Open publication No. 1-297294 proposes a cleaning method practicable with a substrate made of plastic, metal, paper low in infiltration, ceramic or similar material. The method heats, with the intermediary of a thermally soluble separating body, an image formed on such a kind of substrate. However, this approach is not practicable without resorting to a special sheet whose surfaces are provided with a parting ability.
On the other hand, Japanese Patent Laid-Open Publication No. 4-255916 teaches a method and device for removing a film-like image forming substance from a recording medium having a layer which swells when brought into contact with a liquid. The swelling layer is formed at least on the side of the medium where an image is to be formed. The device includes supplying means for supplying to the medium a water-containing liquid (removal accelerating liquid) which causes the swelling layer to swell more than the substance provided on the medium. Separating means presses, after the liquid has been supplied to the medium, a separating member against the medium with or without heating to thereby transfer the substance from the medium to the separating member. It was experimentally determined that this method is capable of removing only the film-like image forming substance from the medium without damaging the texture of the medium to a noticeable degree, thereby restoring the medium to a reusable condition. It should be noted that the word "film-like" refers not only to a condition wherein the entire image forms a single film, but also to a condition wherein the substance is not infiltrated deep into the medium, and a condition wherein the substance is not adsorbed by the medium almost at the molecule level. This kind of adsorption occurs with water ink containing a dye.